[Freeswitch-users] Problem with rtp streams and stair-stepped (or ramped) increased lag

[Nathan Neulinger]

Very interesting... look forward to seeing the comparison of those two captures... I'm in the process of trying to rule 
out vmware as a contributing factor by moving the FS servers to dedicated hardware, but your description sounds like 
there may be some other issue in addition.

In my case, it's all confined within local network, so there shouldn't be much of any latency spikes, at least not 
significant ones.

Looking at the graphs of a few calls today, on at least one of the not-so-bad ones, I saw a very periodic blip on the 
stairstep every 60 seconds. That doesn't cover the large drift ones in the graphs I posted though.

-- Nathan

On 06/25/2013 06:48 PM, William King wrote:
> Nathan,
>
> I had a chance to diagnose the issue live on a system today. While I'm
> not yet sure we are hitting the same issue, I'm now confident the
> problem I'm hitting is not FS related, but looks to be kernel related. I
> was able to get multiple calls up all with large 5+ second delays.
> Restarting the calls did nothing to clear the problem. Restarting
> Freeswitch repeatedly also had no effect. Upon restarting the box, the
> problem was gone.
>
> Also in my diagnostics I've found that it isn't all UDP packets that are
> effected. I now have a switch mirroring the port and a pcap running
> locally on the machine. I'll see tomorrow if it's just a matter of an
> inbound or outbound network stack buffer(or network stack priority) issue.
>
> William King
> Senior Engineer
> Quentus Technologies, INC
> 1037 NE 65th St Suite 273
> Seattle, WA 98115
> Main:   (877) 211-9337
> Office: (206) 388-4772
> Cell:   (253) 686-5518
> william.king at quentustech.com
>
> On 06/25/2013 05:13 AM, Nathan Neulinger wrote:
>> I guess the big question is this:
>>
>> 	Is it _supposed_ to recover?
>>
>>   From Tony's notes, it's sounding like it's very critically dependent on the timer in the switch, which very well be the
>> current cause of my issues.
>>
>> What I probably need to do is have a pair of phones automatically calling each other, and just leaving them up - just to
>> generate a continuous independent background stream. That'll tell me if any glitches are specific to a particular
>> channel, or if they are common across multiple calls - which I'd expect if the timer was swinging.
>>
>> I don't know where my latency is being introduced unfortunately...
>>
>> -- Nathan
>>
>> On 06/25/2013 01:59 AM, Avi Marcus wrote:
>>> It sounds like I saw  this on a home internet connection to a public server when the connection had varying latency.
>>> Once the call jittered, it never recovered.
>>> My stop-gap was to add a small jitter buffer <http://wiki.freeswitch.org/wiki/Jitterbuffer>, e.g. <action
>>> application="jitterbuffer" data="100:200:20"/> to the user dialplan.
>>> This /seemed /to make FS handle rewriting the timestamps for drift rather than relying on the Linksys ATA to do that.
>>>
>>> Probably the wrong solution, but all I had time/understanding for.
>>> -Avi
>>>
>>>
>>> On Tue, Jun 25, 2013 at 4:42 AM, Nathan Neulinger <nneul at mst.edu <mailto:nneul at mst.edu>> wrote:
>>>
>>>
>>>
>>>      On 06/24/2013 08:24 PM, Anthony Minessale wrote:
>>>       > fsctl debug_level 10
>>>       > Also make sure ve host has high res timing.
>>>
>>>      Turned up logging, will wait for next occurrence.
>>>
>>>      Not sure on the latter - it's a vmware ESXi 5.1 box running FC 17 x86_64 as the guest.
>>>
>>>      /dev/rtc /dev/rtc0 exist
>>>      posix and soft timers are loaded in fs
>>>
>>>      I've got a bunch of unused Dell 1950's on hand, so could use a few of those machines if needed to get vmware out of the
>>>      picture.
>>>
>>>      -- Nathan
>>>
>>>      ------------------------------------------------------------
>>>      Nathan Neulinger nneul at mst.edu <mailto:nneul at mst.edu>
>>>      Missouri S&T Information Technology (573) 612-1412 <tel:%28573%29%20612-1412>
>>>      System Administrator - Architect
>>>
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>>
>
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-- 
------------------------------------------------------------
Nathan Neulinger                       nneul at mst.edu
Missouri S&T Information Technology    (573) 612-1412
System Administrator - Architect